Techniques for optical communication by processing captured time-series images (frames) are known. When a technique described in, for example, Unexamined Japanese Patent Application Kokai Publication No. 2007-147994 is employed as a transmitter including, as a light source, an outdoor lighting or the like that emits light modulated in accordance with information, a camera built in a communicator captures an image of the transmitter and received light is demodulated to obtain information.